A piezoelectric motor of small dimensions capable of satisfying such an application is described in the patent application Ser. No. 07/759,561, filed Sep. 13, 1991, now U.S. Pat. No. 5,233,257. Such piezoelectric motor which is shown on the attached FIGS. 1, 2 and 3 and which will be described hereinafter in a detailed fashion, comprises in a standard manner, on the one hand, a stator associated with piezoelectric means and, on the other hand, a rotor which is assembled for rotation on such stator. The piezoelectric means are constituted by a polarized ceramic which can be electrically excited in order to induce a vibratory motion in the stator while the rotor is provided with flexion blades arranged to bear elastically on the stator. Such blades are adapted to assure transmission of such vibratory motion to the rotor.
The elastic bearing of the rotor on the stator via such transmission blades is assured by sustaining means including a spring in the form of a dome. Such spring is axially maintained by a headed screw engaged in a fixed stepped spindle which forms a support and which urges the rotor along such spindle. A roller bearing is arranged between the head of the screw and the spring enabling concomitant rotation of the assembly rotor-spring.
Such motor exhibits a space requirement in height such that it cannot equip timepieces exhibiting a naturally small thickness.
Thus, the present invention has as purpose to overcome this drawback in providing a piezoelectric motor of small thickness capable of equipping a timepiece without spoiling its dimensional characteristics.